The present invention relates to an ultrasonic probe to be used in an ultrasonic diagnostic apparatus or the like.
An ultrasonic probe is used, for example, in an ultrasonic diagnostic apparatus for a human body. One of the conventional ultrasonic probes is disclosed in Japanese Patent Laid-Open Publication No. Hei 8-122310. FIG. 17 shows a structure of this conventional ultrasonic probe. In FIG. 17, a piezoelectric element 31 is an element for transmitting and receiving an ultrasonic wave, and each face thereof is provided with an electrode. An acoustic matching layer 37 is made of conductive material and is provided on a face of one of the electrodes to efficiently transmit and receive an ultrasonic wave for a subject to be examined (human body). The ultrasonic probe further comprises a conductive layer 40 provided on a high molecular film 41 by deposition or other proper operations so as to be brought into contact with the acoustic matching layer 37. An acoustic lens 38 is provided on a face of the high molecular film to focus the ultrasonic wave. An FPC 34 is provided on the other electrode so as to form a conductive pattern, and a backing material 39 is provided on a face of the FPC 34. This structure allows an electrical connection to be maintained even if the piezoelectric element 31 is cracked by an external mechanical impact, and thereby provides a feature that the piezoelectric element is less likely to fail and stable quality is provided.
Referring to FIG. 17 more specifically, the piezoelectric element 31 is provided with a positive electrode 32 on one face thereof and with a ground electrode 33 on the other face thereof. Each of these electrodes 32, 33 is made of baked-silver formed by baking a composite of glass and silver, or of gold plating, sputtering or deposition, and has a thickness of 0.5 to 10 xcexcm to provide a short pulse characteristic. The positive electrode 32 is provided, on a back face thereof, with a laminate of a positive electrode side conductive layer 35 and a positive electrode side base material layer 36 stacked in this order. The positive electrode side base material layer 36 is made of high molecular film or the like, and the positive electrode side conductive layer 35 is formed on this base material layer by plating, sputtering or deposition with metallic material such as copper or gold, or by fixing a metal foil thereto, and further is formed into a proper pattern, if necessary. Further, the backing material 39 is provided on a back face of the positive electrode side base material layer 36 so that a short pulse characteristic is achieved by braking the piezoelectric element 31.
Further, the acoustic matching layer 37 made of conductive material such as graphite is laminated on a front face of the ground electrode 33 (on the side of a subject to be examined), and a ground electrode side conductive layer 40 and a ground electrode side base material layer 41 are laminated on a front face of the acoustic matching layer 37.
The ground electrode side base material layer 41 is made of high molecular film or the like, and the ground electrode side conductive layer 40 is formed on this base material layer 41 by plating, sputtering or deposition with such metal as copper or gold, or by fixing a metallic foil thereto, where the ground electrode side conductive layer 40 is disposed below the base material layer 41 as shown in FIG. 17. Further, an acoustic lens 38 is provided on a front face of the ground electrode side base material layer 41 to focus the ultrasonic wave.
In this structure, a mechanical deformation is produced in the piezoelectric element 31 by an electric signal supplied between the positive electrode side conductive layer 35 and the ground electrode side conductive layer 40 from a main body of an ultrasonic diagnostic apparatus (not shown), and thereby an ultrasonic wave is transmitted.
The ultrasonic wave transmitted from this piezoelectric element 31, after the propagation efficiency thereof into a human body is enhanced by the acoustic matching layer 37 and the wave is focused by the acoustic lens 38, is transmitted into the human body (not shown). The ultrasonic wave transmitted into the human body produces a reflective wave when it is reflected by an interface of tissues in the human body. The reflective wave, after passing the same path as the transmitted ultrasonic wave in a reverse direction, is received by the piezoelectric element 31 and is transformed back into an electric signal to be sent as a received signal to the ultrasonic diagnostic apparatus. Based on this received signal, the ultrasonic diagnostic apparatus forms an image indicative of the information inside the human body to make a diagnosis. Another conventional ultrasonic probe is disclosed in Japanese Patent Laid-Open Publication No. Hei 11-276479.
FIG. 18 is a schematic perspective view of another conventional ultrasonic probe. In explaining this drawing, the word xe2x80x9cupxe2x80x9d means a direction from a lower part of the drawing to an upper part thereof. In FIG. 18, a piezoelectric element 51 is an element for transmitting and receiving an ultrasonic wave. A first electrode 53 and a second electrode 52 each being provided on one face of the piezoelectric element 51, respectively, are electrodes for applying a voltage to the piezoelectric element 51. The first electrode 53 works as a GND and forms a turning electrode which passes along a side face of the piezoelectric element extending parallel with a short axis direction thereof, and reaches a portion of a face of a backing material. The first electrode 53 of the piezoelectric element 51 is electrically connected to a copper foil 55, and the second electrode 52 is a signal electrode electrically connected to a flexible print circuit (FPC) 54 with a wiring pattern formed thereon. Each electrode is disposed on one of end faces of the piezoelectric element, respectively, in the short axis direction. Further, the piezoelectric element 51 and a plurality of acoustic matching layers are cut along a direction parallel with the short axis to form channel dividing grooves 56, so that a plurality of piezoelectric elements are arranged to align with the short axis direction.
A first acoustic matching layer 57a is provided on an upper face of the first electrode 53 (to face the subject to be examined) so that the ultrasonic wave may be efficiently transmitted and received thereby. A second acoustic matching layer 57b is provided on an upper face of the first acoustic matching layer 57a so that the ultrasonic wave may also be efficiently transmitted and received thereby. An acoustic lens 58 is provided on the second acoustic matching layer 57b to focus the ultrasonic wave. Further, a backing material 59 is provided on a lower face of the second electrode 52 in order to absorb undesired ultrasonic waves as well as to support the piezoelectric element 51.
In the conventional ultrasonic probe shown in FIG. 17; however, the high molecular film 41 is provided to be extended as an electrical terminal and is not contemplated as an acoustic matching layer. Accordingly, there occurs a problem in that the efficiency in transmitting and receiving the ultrasonic wave is reduced, and further the frequency characteristic is degraded. Further, there is another problem in that an insulator of a signal electrical terminal disposed between the piezoelectric element and the backing material is generally thick, which has a negative effect on the damping of the backing material and degrades the acoustic characteristic of the ultrasonic probe, especially the frequency characteristic thereof.
Further, in the conventional ultrasonic probe described above, the acoustic matching layer 37 is provided in order to efficiently propagate the ultrasonic wave transmitted from the piezoelectric element 31 (generally having a high acoustic impedance of about 25 to 35 Mrayl) into a human body (having an acoustic impedance of about 1.5 Mrayl), and the acoustic matching is optimized by adjusting the acoustic impedance and the thickness of the acoustic matching layer 37, and thereby the ultrasonic probe having waves of a short pulse length and high propagation efficiency is achieved. However, the acoustic matching is impaired and the pulse length and the propagation efficiency are degraded due to an existence of the ground electrode side conductive layer 40 made of metallic material between the acoustic matching layer 37 and the acoustic lens 38.
This problem is also seen at the positive electrode side conductive layer. The conductive layer has a greater adverse effect as the frequency of the ultrasonic wave increases.
The thickness of each conductive layer must be smaller than 5 xcexcm in order to reduce the degradation in the pulse length and the propagation efficiency. On the other hand, however, the thinner conductive layer makes the electrical resistance (electrical impedance) larger, and thereby a driving electrical signal on an electrical conductive path is lowered to reduce the electrical signal applied to the piezoelectric element 1, and as a result, the electro-mechanical conversion efficiency from a viewpoint of the diagnostic apparatus is decreased.
Further, when the electrical impedance on the electrical conductive path is increased, the capability of removing external electrical noise is deteriorated, and accordingly, external electromagnetic noise causes the diagnosis image to be deteriorated, which makes the simultaneous optimization of an acoustic matching condition and an electrical conductive path more difficult, and also prevents an accurate diagnosis based on the ultrasonic image, which eventually might result in a serious problem of inducing a wrong diagnosis.
The present invention has been made to solve the problems described above, and an object thereof is, in an ultrasonic probe where progress toward higher resolution is being developed, to provide diagnostic information based on a highly accurate ultrasonic image by simultaneously optimizing the acoustic matching condition and the electrical conductive path.
Further, in the conventional system, since the electrodes are disposed on respective end faces of the piezoelectric element with respect to the short axis direction thereof, and are extended out therefrom, if the piezoelectric element is subjected to, for example, an external mechanical impact by a post-processing operation or the like, and thereby the first electrode fails to keep an electrical connection due to breakage thereof, the ability of transmitting and receiving the ultrasonic wave by the piezoelectric element is limited to only a portion of the electrode electrically connected to the copper foil or the FPC, and this sometimes causes to lower the performance of the piezoelectric element. Further, since the copper foil and the FPC are electrically connected by a conductive adhesive or the like at end faces of the piezoelectric element with respect to the short axis thereof, sometimes another problem results in that, when a conductive adhesive of high curing temperature is employed, an electrode is deteriorated by heat and thereby the performance of the piezoelectric element is lowered.
An ultrasonic probe of the present invention has been made to solve these problems. Another object of the present invention is to provide a high-quality piezoelectric probe, the performance of which is not degraded even if the piezoelectric element is cracked by a mechanical impact applied thereto.
The present invention has been made to solve the problems of the conventional system described above. A further object of the present invention is to provide a high-quality ultrasonic probe which has an acoustic impedance substantially equal to that of the acoustic matching layer, and does not deteriorate in performance, including sensitivity and frequency characteristics.
Further, in the conventional ultrasonic probe described above, there is another problem that an insulator of the signal electrical terminal disposed between the piezoelectric element and the backing material is generally thick, which has a negative effect on the damping performance of the backing material, and degrades the acoustic characteristic of the ultrasonic probe, especially the frequency characteristic thereof.
The present invention has been made to solve these problems, and a still further object of the present invention is to provide an ultrasonic probe which does not deteriorate the acoustic characteristic, especially of the frequency characteristic.
In order to solve the problems described above, the present invention provides an ultrasonic probe in which a high molecular material layer including a conductive layer is disposed on a piezoelectric element, and an acoustic matching layer is disposed on the high molecular material layer, wherein the high molecular material layer has an acoustic impedance substantially equal to that of the acoustic matching layer and the total thickness of these two layers is substantially equal to a quarter wavelength of an ultrasonic wave.
In an alternative ultrasonic probe of the present invention, a high molecular material layer including a conductive layer is disposed on a first acoustic matching layer, and a second acoustic matching layer is disposed on the high molecular material layer, wherein the high molecular material layer has an acoustic impedance substantially equal to that of the second acoustic matching layer and the total thickness of these two layers is substantially equal to a quarter wavelength of an ultrasonic wave.
In another alternative ultrasonic probe of the present invention, a conductive layer electrically connected to an electrode face of a piezoelectric element is disposed between the electrode face of the piezoelectric element and an acoustic matching layer, and a high molecular material layer including a conductive layer formed thereon is disposed on the acoustic matching layer side, wherein the high molecular material layer has an acoustic impedance substantially equal to that of the acoustic matching layer and the total thickness of these two layers is substantially equal to a quarter wavelength of an ultrasonic wave.
In a further alternative ultrasonic probe of the present invention, a high molecular material layer is disposed between a first acoustic matching layer and a second acoustic matching layer located on a subject side, wherein an acoustic impedance of the high molecular material layer is between that of the first acoustic matching layer and that of the second acoustic matching layer, or is substantially equal to that of said first acoustic matching layer or that of the second acoustic matching layer.
Because of these structures described above, the sensitivity of transmitting and receiving the ultrasonic wave can be improved and further, desired frequency characteristics can be provided. Accordingly, an ultrasonic diagnostic apparatus with an image of higher resolution and higher sensitivity can be provided, and also an ultrasonic probe which is less likely to fail and has a stable quality can be obtained since an electrical connection can be maintained even if the piezoelectric element is cracked by an external mechanical impact.
A still further alternative ultrasonic probe of the present invention includes a high molecular material layer disposed on a piezoelectric element and an acoustic matching layer disposed on the high molecular material layer. The high molecular material layer comprises a base material made of high molecular material, and a conductive layer made of conductive material is formed thereon, wherein the high molecular material layer has an acoustic impedance substantially equal to that of the acoustic matching layer. Accordingly, the sensitivity of transmitting and receiving an ultrasonic wave can be improved and desired frequency characteristics can be provided. Thus, an ultrasonic diagnostic apparatus with an image of higher resolution and higher sensitivity can be provided, and also an ultrasonic probe which is less likely to fail and has a stable quality can be obtained since an electrical connection can be maintained even if the piezoelectric element is cracked by an external mechanical impact.
Further, a yet another alternative ultrasonic probe of the present invention includes a high molecular material layer disposed on a piezoelectric element and an acoustic matching layer disposed on the high molecular material layer. The high molecular material layer comprises a base material made of high molecular material, and a conductive layer made of conductive material is formed thereon. The high molecular material layer has an acoustic impedance substantially equal to that of the acoustic matching layer and the total thickness of these two layers is substantially equal to a quarter wavelength of the ultrasonic wave, and thereby the sensitivity of transmitting and receiving the ultrasonic wave can be improved and further desired frequency characteristics can be provided. Accordingly, an ultrasonic diagnostic apparatus with an image of higher resolution and higher sensitivity can be provided, and also an ultrasonic probe which is less likely to fail and has a stable quality can be obtained since an electrical connection can be maintained even if the piezoelectric element is cracked by an external mechanical impact.
Further, an additional alternative ultrasonic probe of the present invention includes a high molecular material layer disposed on a piezoelectric element and an acoustic matching layer disposed on the high molecular material layer. The high molecular material layer comprises a base material made of high molecular material, and a conductive layer made of conductive material is formed thereon. The high molecular material is made of polyimide, polyethylene-terephthalate, polysulphon, polycarbonate, polyester, polystyrene, poly-phenylene-sulphide or the like, and the high molecular material layer has an acoustic impedance substantially equal to that of the acoustic matching layer, and thereby the sensitivity of transmitting and receiving the ultrasonic wave can be improved and further desired frequency characteristics can be provided. Accordingly, an ultrasonic diagnostic apparatus with an image of higher resolution and higher sensitivity can be provided, and also an ultrasonic probe which is less likely to fail and has a stable quality can be obtained since an electrical connection can be maintained even if the piezoelectric element is cracked by an external mechanical impact.
Further, another alternative ultrasonic probe of the present invention includes a high molecular material layer disposed on a first acoustic matching layer and a second acoustic matching layer disposed on the high molecular material layer. The high molecular material layer comprises a base material made of high molecular material, and a conductive layer made of conductive material is formed thereon, wherein the high molecular material layer has an acoustic impedance substantially equal to that of the second acoustic matching layer, and thereby the sensitivity of transmitting and receiving the ultrasonic wave can be improved and further desired frequency characteristics can be provided. Accordingly, an ultrasonic diagnostic apparatus with an image of higher resolution and higher sensitivity can be provided, and also an ultrasonic probe which is less likely to fail and has a stable quality can be obtained since an electrical connection can be maintained even if the piezoelectric element is cracked by an external mechanical impact.
Further, another alternative ultrasonic probe of the present invention includes a high molecular material layer disposed on a first acoustic matching layer and a second acoustic matching layer disposed on the high molecular material layer. The high molecular material layer comprises a base material made of high molecular material, and a conductive layer made of conductive material is formed thereon. The high molecular material layer has an acoustic impedance substantially equal to that of the second acoustic matching layer, and the total thickness of these two layers is substantially equal to a quarter wavelength of the ultrasonic wave, and thereby the sensitivity of transmitting and receiving the ultrasonic wave can be improved and further desired frequency characteristics can be provided. Accordingly, an ultrasonic diagnostic apparatus with an image of higher resolution and higher sensitivity can be provided, and also an ultrasonic probe which is less likely to fail and has a stable quality can be obtained since an electrical connection can be maintained even if the piezoelectric element is cracked by an external mechanical impact.
Further, another alternative ultrasonic probe of the present invention includes a high molecular material layer disposed on a first acoustic matching layer and a second acoustic matching layer disposed on the high molecular material layer. The high molecular material layer comprises a base material made of high molecular material, and a conductive layer made of conductive material is formed thereon. The high molecular material is made of polyimide, polyethylene-terephthalate, polysulphon, poly-carbonate, polyester, polystyrene, poly-phenylene-sulphide or the like, and the high molecular material layer has an acoustic impedance substantially equal to that of the said second acoustic matching layer, and thereby the sensitivity of transmitting and receiving the ultrasonic wave can be improved and further desired frequency characteristics can be provided. Accordingly, an ultrasonic diagnostic apparatus with an image of higher resolution and higher sensitivity can be provided, and also an ultrasonic probe which is less likely to fail and has a stable quality can be obtained since an electrical connection can be maintained even if the piezoelectric element is cracked by an external mechanical impact.
Further, another alternative ultrasonic probe of the present invention includes a first conductive layer which is made of conductive material and is disposed between an electrode face of a piezoelectric element and an acoustic matching layer so as to be electrically connected to the electrode face of the piezoelectric element. A high molecular material layer is disposed on the acoustic matching layer side. The high molecular material layer comprises a base material made of high molecular material, and a second conductive layer made of conductive material is formed thereon. The high molecular material layer has an acoustic impedance substantially equal to that of the acoustic matching layer, and thereby the sensitivity of transmitting and receiving the ultrasonic wave can be improved and further desired frequency characteristics can be provided. Accordingly, an image on an ultrasonic diagnostic apparatus may be improved to be of higher resolution and of higher sensitivity, and further noise can be reduced since the conductive material works as a shield.
Further, another alternative ultrasonic probe of the present invention includes a conductive layer which is made of conductive material and is disposed between an electrode face of a piezoelectric element and an acoustic matching layer so as to be electrically connected to the electrode face of the piezoelectric element. A high molecular material layer is disposed on the acoustic matching layer side. The high molecular material layer comprises a base material made of high molecular material, and a conductive layer made of conductive material is formed thereon. The high molecular material layer has an acoustic impedance substantially equal to that of the acoustic matching layer, and thereby the sensitivity of transmitting and receiving the ultrasonic wave can be improved and further desired frequency characteristics can be provided. Accordingly, an image of an ultrasonic diagnostic apparatus may be improved to be of higher resolution and of higher sensitivity, and further noise can be reduced since the conductive material works as a shield.
Further, another alternative ultrasonic probe of the present invention includes a first acoustic matching layer located on a piezoelectric element side, a second acoustic matching layer located on a subject side, and a high molecular material layer between the first acoustic matching layer and the second acoustic matching layer. The high molecular material layer comprises a base material made of high molecular material, and a conductive layer made of conductive material is formed thereon, wherein an acoustic impedance of the high molecular material layer is between those of the first acoustic matching layer and said second acoustic matching layer, or substantially equal to that of the first acoustic matching layer or the second acoustic matching layer, and thereby the sensitivity of transmitting and receiving the ultrasonic wave can be improved and further desired frequency characteristic can be provided. Accordingly, an ultrasonic diagnostic apparatus with an image of higher resolution and higher sensitivity can be provided, and also an ultrasonic probe which is less likely to fail and has a stable quality can be provided since an electrical connection can be maintained even if the piezoelectric element is cracked by an external mechanical impact.
Further, another alternative ultrasonic probe of the present invention comprises a piezoelectric element having electrodes on both sides thereof, a backing material on one electrode side of the piezoelectric element, and a signal electrical terminal between the piezoelectric element and the backing material. The signal electrical terminal comprises an insulator facing the backing material and a conductive material facing one electrode face of the piezoelectric element so as to be electrically connected to the piezoelectric element. The insulator of the signal electrical terminal has a thickness equal to or less than {fraction (1/25)} wavelength of an ultrasonic wave at an area facing an ultrasonic wave emitting surface of the piezoelectric element.
Because of the structure described above, there can be provided an ultrasonic probe having an improved sensitivity for transmitting and receiving the ultrasonic wave, a higher resolution and further, an improved frequency characteristic. Accordingly, an ultrasonic diagnostic apparatus with an image of higher resolution and higher sensitivity can be provided, and also an ultrasonic probe which is less likely to fail and has a stable quality can be provided since an electrical connection can be maintained even if the piezoelectric element is cracked by an external mechanical impact.
Further, another ultrasonic probe of the present invention has an insulating material made of material selected from a group consisting of polyimide, polyethylene-terephthalate, poly-sulphon, poly-carbonate, polyester, polystyrene, and poly-phenylene-sulphide.
An ultrasonic probe of the present invention has a feature in that an acoustic impedance of an insulator is less than those of the piezoelectric element and the backing material.
In another aspect of the present invention, an ultrasonic probe comprises a piezoelectric element having electrodes on both sides thereof, a backing material on one electrode side of the piezoelectric element, and a first signal electrical terminal between the piezoelectric element and the backing material. The first signal electrical terminal comprises an insulator facing the backing material and a conductive material facing one electrode face of the piezoelectric element so as to be electrically connected to the piezoelectric element. An insulator of the first signal electrical terminal has a thickness equal to or less than {fraction (1/25)} wavelength of an ultrasonic wave at an area facing an ultrasonic wave emitting surface of the piezoelectric element. A second signal electrical terminal is disposed on a lateral outer side of the backing material. The second signal electrical terminal comprises an insulator and a conductive material. The conductive material of the first signal electrical terminal and the conductive material of the second signal electrical terminal are electrically connected to each other.
Because of the structure described above, there can be provided an ultrasonic probe having an improved sensitivity for transmitting and receiving the ultrasonic wave, a higher resolution and further, an improved frequency characteristic. Accordingly, an ultrasonic diagnostic apparatus with an image of higher resolution and higher sensitivity can be provided, and also an ultrasonic probe which is less likely to fail and has a stable quality can be provided since an electrical connection can be maintained even if the piezoelectric element is cracked by an external mechanical impact. Further, another advantage is that the ultrasonic probe can be easily manufactured.
Further, according to another feature of an ultrasonic probe of the present invention, an area of a conductive layer covering an electrode portion of a piezoelectric element has different thicknesses from one area thereof to another area thereof so that the thickness of the conductive layer may be optimized in respective areas from an acoustic viewpoint as well as an electrical conductive path viewpoint.
That is, there may be provided an ultrasonic probe comprising a piezoelectric element having a positive electrode on one face thereof and having a ground electrode another face thereof, and a conductive layer laminated so as to partially overlap at least one of the electrodes, wherein the thickness of the conductive layer in an acoustic effective area is smaller than that in an area at the outside of the acoustic effective area.
According to the structure described above, the area of the conductive layer overlapping the one of the electrodes (acoustic effective area) may be made thin so that an acoustical negative effect can be reduced, and in the other area the conductive layer is used as an electrically conductive path may be made thick so that the electrical impedance can be reduced. By this structure, both the acoustic matching condition and the electrical conductive path can be optimized simultaneously.
In addition to the similar operation and effect described above, the structure including the conductive layer formed on a base material has remarkable advantage in that the conductive portion formed by the thinner portion of the conductive layer is not likely to be creased, crinkled or eventually plastically deformed, which makes it easy to handle the conductive layer and the ultrasonic probe during the production process thereof.
Further, another ultrasonic probe of the present invention comprises a piezoelectric element having a positive electrode on one face thereof and having a ground electrode on another face thereof, an acoustic matching layer on a front face of the ground electrode, a base material layer on a front face of the acoustic matching layer, and a conductive layer disposed on the base material layer. A portion of the conductive layer, at least in an acoustic effective area, is thinner than that of an area outside of the acoustic effective area. By this structure, in addition to the similar operation and effect described above, there may be provided another advantageous effect in that the base material layer works as a second acoustic matching layer.
Further, another alternative ultrasonic probe of the present invention comprises a piezoelectric element having electrodes on both sides thereof, an acoustic matching layer contacting one electrode face of the piezoelectric element, and a backing material disposed on the other side of the piezoelectric element. The acoustic matching layer is made of conductive material and is electrically connected to the one electrode face of the piezoelectric element, and an end portion of the acoustic matching layer is electrically connected to a conductive film disposed on a side portion of the backing material. Thereby, the one electrode face of the piezoelectric element is extended out to the conductive film.
This structure allows a curved face to be easily formed after a cutting machining operation, and further allows an electrical connection to be maintained through the conductive acoustic matching layer even if the piezoelectric element is cracked by an external mechanical impact or the like, and thereby the performance of the piezoelectric element is not degraded and is less likely to fail, whereby the quality thereof can be stabilized.
Further, there may be provided an ultrasonic probe which can be easily manufactured without degrading the performance thereof since the piezoelectric element need not be exposed to a hot environment.
Further, an alternative ultrasonic probe of the present invention has an acoustic matching layer made of graphite.
Further, another alternative ultrasonic probe of the present invention has an insulating layer provided in a space between an acoustic matching layer, extended out from a piezoelectric element, and a backing material.
This structure allows the insulating layer to support the acoustic matching layer and also reinforces the strength of the acoustic matching layer against a mechanical impact applied during a machining process, which facilitates manufacturing of the ultrasonic probe.
Further, another alternative ultrasonic probe of the present invention has an insulating layer made of material selected from the group consisting of ceramic, acrylic resin, plastic, epoxy resin, cyanoacrylate and urethane resin.
Further, another alternative ultrasonic probe of the present invention comprises a piezoelectric element having electrodes on both sides thereof, a first acoustic matching layer contacting one of the electrodes, a second acoustic matching layer on an opposite side of the first acoustic matching layer with respect to the piezoelectric element, and a backing material disposed on the other side of the piezoelectric element. The first acoustic matching layer is made of conductive material and is electrically connected to the one electrode, and an end portion of the first acoustic matching layer is electrically connected to a conductive film disposed on a side portion of the backing material so that the one electrode may be extended to the conductive film.
This structure allows a curved face to be easily formed after a cutting machining operation, and further allows an electrical connection to be maintained through the conductive acoustic matching layer even if the piezoelectric element is cracked by an external mechanical impact or the like, and thereby the performance of the piezoelectric element is not degraded and is less likely to fail, whereby a stable quality can be obtained.
Further, an alternative ultrasonic probe of the present invention includes a second acoustic matching layer having a conductive layer electrically connected to the first acoustic matching layer.
This structure allows an electrical connection to be maintained even if the piezoelectric element and the first acoustic matching layer are cracked by an external mechanical impact, and thereby the ultrasonic probe is less likely to fail and a stable quality can be obtained.
Further, an alternative piezoelectric probe of the present invention includes a second acoustic matching layer made of material selected from the group consisting of polyimide, polyethylene-terephthalate, polysulphon, polycarbonate, polyester, polystyrene, and poly-phenylene-sulphide.